Blender Imported file.OBJ I not showing up
If you expand the tree list in the upper right for that object, you can see what materials are attached to it and possibly reattach them without having to re-extract and re-import.  

Depending on the size of your object, it may also be hidden by the clipping planes.  When I can't find something, I go to the menu on the right of the 3D window and change the clip to a really high number (usually 1,000,000 or so).  Since the object shows up in the list on the right, another thing you can do is select it in that list, move the mouse back to the 3D window, and hit the period key on the number pad to zoom to that object.